The snake ate so clearly what you are doing is basically correct stressed snakes don't eat and cold snakes don't eat and hot snakes don't eat. Changing a system that is working for an unknown is tricky because what ever you did you have a balanced system not messing with it will only stress the animal and cause issues I'd advise WAITING. Give the snake a chance to settle in to new home new keeper and new situation before you change its substrate and heating systems.

UTH do nothing for ambient temps so you might want to think about that before changing if you room is too cool you will have to still use an over head system. I'd look at CHEs but I'd also wait at least a few months before I did anything unless there is a problem between now and then.

Eating snakes are happy.